Unique? The games are as color-by-number as you can get.
You clearly don't even play them.
Compared to what?
The character development is nonexistent.
Not at all. For example, Totori and Meruru are wonderful coming-of-age stories, and have all the common ingredients of those concerning the main character's development, and they are well-realized to boot.
They tweak gameplay with each subsequent entry in their ever-running series, but there's nothing "unique."
This is perhaps the most laughable instance of your wrongness. The entire setup of the Atelier games is almost entirely unique in JRPGs:
- They are non-linear, with a large number of distinct endings.
- They feature a complex and intricate crafting system which is at least as important to the overall gameplay as the battles are.
- They have a time-dependent quest and story structure.
How on earth is that not unique?
As for "tweaking", the alchemy system (a central component of the games) has changed
fundamentally between the Arland and Dusk sub-series. And it looks like the next entry will do away with the time limit structure and replace it with a new way to distribute quests.
Character designs are standard and uninspired. The stories are unoriginal, and the plots are ridiculous.
The stories aren't ridiculous at all. Not just compared to JRPGs, but to games in general. They are actually quite grounded. Also, "unoriginal" is just a ridiculous accusation to level at a developer that came up with the Ar Tonelico universe.